Re: left join with smaller table or index on (XXX is not null) to avoid upsert

On Mon, Jan 19, 2009 at 4:43 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> But having said that: 8.4 will provide a standard trigger that
> short-circuits vacuous updates, which you can apply to tables in which
> you think vacuous updates are likely.  It's your responsibility to place
> the trigger so that it doesn't interfere with any other trigger
> processing you may have.

Tom, Can you point us to
http://developer.postgresql.org/pgdocs/postgres/ where it is described
in more detail ?

--
GJ